Electric timing and counting device



Marh 1, 1938. A. s. FITZ GERALD ELECTRIC TIMING AND COUNTING DEVICE 3 Sheets-Sheet 1 Filed March 9, 1932 Fig]. 111m za- M ENE Inventor: Alan SFitzGePald, b WM His Attorne g.

March 1, 1938. 5, LD 2,110,015

' ELECTRIC TIMING AND COUNTING DEVICE Filed March 9, 1932 3 Sheets-Sheet 2 Invent 01:

Alan 8 FibzC-Eewald, km M a/ah His Abt own 93.

March 1, 1938. 3 11 GERALD 2,110,015

ELECTRIC TIMING AND COUNTING DEVICE Filed March 9, 1932 3 Sheets-Sheet 3 Pi .5. w 59 g lfilllw- /s A 6/ /4 W l m Alan S. FitzGe-rald, 10 MW His Attorne s.

Patented Mar. 1, loss I 2,110,015

UNITED STATES PATENT OFFICE EIECTBIC TIMING AND COUNTING DEVICE Alan 8. Fit: Gerald, Wynnewood, Pa... assignor to General Electric Company, a corporation of New York Application March 9, 1932, Serial N0. 597,855

14 Claims. (Cl. 177-353) My invention relates to electric timing and a frequency dividing arrangement; Fig. a relacounting devices and concerns particularly the tively simple form of code selector; Fig. 6 repemployment of electrical means including dis-' resents a code selector in which special precaucharge tubes as counting or timing elements. It tions are taken to prevent errors; and Fig. 7

5 is an object of my invention to provide apparepresents a totalizing device in which mechani- 5 ratus for measuring time and time differences or cal circuit interrupters are utilized. for controlling the timing of operations. Referring now more in detail to the drawings Another object of my invention is to provide in which like reference characters refer to like apparatus for counting impulses or for aflectparts throughout, in the arrangement shown in 10 ing the operation of an apparatus after the oper- Fig. l a charging current is supplied by a source 10 ation has been repeated a predetermined numwhich may, if desired, be a constant potential ber of times. direct current source having a positive terminal Another object of my invention is to provide ii and a negative terminal II. A charge transa frequency converter or frequency divider for ferring condenser I3 is connected to the source is use with alternating current circuits and particuof current through a current controlling device, larly for use where the ratio of conversion is ref rably a grid controlled discharge tube l4. l r T s aspect my invention is claimed in A second current controlling device, preferably y divisional app R 679,393 filed y also a grid controlled discharge tube l5 and a 11, 1933, Patent No. 2.078.792 dated April 27. charge collecting condenser i6 are connected in 1937- other and further objects w l become -P series across the terminals of the charge trans- 20 parent as the description proceeds. ferring condenser l3. Although I have shown In accordance with my invention in its prea source of direct current for charging the conferred f -rm a plurality of condensers and curdenser [3, my invention is obviously not limited rent controlling devices, for example electric disthereto as an alternating current source can also charge tubes are so connected in relation to a be employed when a discharge tube or other 25 source of current that one of the condensers is inherently rectifying means is utilized as the curalternately charged and discharged, and charges rent controlling means I. are transferred to one or more other condensers The tube H has its plate l1 connected to the in such a manner that the potential acquired by positive terminal ll of the direct current source the latter condensers is an indication of the numand its cathode i8 connected to a terminal of the 30 ber of impulses supplied to the apparatus. condenser l3. The passage of current through Depending on the purpose for which the apthe tube H is controlled by the potential of the paratus is employed, the operation of the current grid l9. Similarly, the tube I5 is provided with controlling devices may be effected by individual a plate 20 connected to cathode iii of tube It, impulses to be counted or by reversals in polarity a cathode 2i connected to one terminal of charge 35 of an alternating current circuit. Means responcollecting condenser l6, and a control grid 22. sive to voltage are provided to give an indica- The control grids i9 and 22 are normally biased tion or to in late the operation of other appato a potential below that of the corresponding ratus when a charge of a predetermined magnicathodes l8 and 2i by means of suitable sources tude has been transferred to and stored by one of voltage such as cells 23 and 24. 4c of the charge collecting condensers. The fea- The potentials of the rids 9 and 22 are contures of my invention which I believe to be novel trolled by means of a transformer 25 having a and patentable will be pointed out in the claims primary winding 26 and oppositely connected appended hereto. secondary windings 21 and 28. The primary wind- My invention itself, however, will be best uning 28 may either be connected to a source of 45 derStOOd y referring to the l w n palternating current causing the potentials of the tion taken in connection with the accompanying grids l9 and 22 to vary oppositely in regularly drawings in which Fig- 1 r pre ent h me lrecurring cycles or it may be arranged to be concallv one form of coun i g 0r tim device nected to and disconnected from a source of diwhich may also be used as the basis for-frerect current in order to vary oppositely the po- 50 quency converting apparatus, may be arranged tentials of grids l9 and 22 in response to a given as a code selector, or used in connection with impulse signal, operation of a machine or other other apparatus; Fig. 2 is a curve explaining the event depending p the p l on in which action of the apparatus; Fig. 3 is a modified the apparatus s tobe ployed.

form of the apparatus shown in Fig. 1; Fig. 4 is A y ta le means responsive to the volt 55 across condenser I8 may be employed to give a response after a predetermined number. of impulses have been given to the apparatus, after a current has flowed through winding 28 for a predetermined number of cycles or after a predetermined time has elapsed. This voltage responsive means may take the form, for example, of a discharge tube 29 having a control grid 30 connected to one side of the condenser l8. The cathode 31 of the discharge tube 28 is given the desired potential by connecting it to a point on the potentiometer 32 which is connected between terminals II and i2 of the direct current source. When there is no charge on the condenser l8 and the potential difference between its plates is zero the grid 30 will be at the same potential as the terminal l2 of the direct current source, which will be negative with respect to the oathode 3l. Accordingly, the tube 29 will be nonconducting in accordance with well known characteristics of such tubes. After a predetermined charge has been acquired by charge collecting condenser IS the potential of the grid 30 will rise to the point where its potential with respect to the cathode 3| will be such as to cause the tube 29 to become conducting thereby permitting a source of current, for example, the battery 33 to cause a current to flow through a current responsive device 34, closing the contacts 35 arranged to cause the performance of any desired operation. Although I have shown a contact making device controlled by a discharge tube, it will be understood that my invention is not limited to this arrangement.

If desired, means may be employed for restoring the apparatus to the initial conditions after an operation. For example, a. switch 29- controlled manually, by other apparatus or by the device 34, may be utilized to short-circuit the condenser l8 after the operation of device 38, thereby restoring it to zero potential. Other means for discharging condenser l8 will be described in connection with modified apparatus, and still other means will readily suggest themselves to those skilled in the art. However, it will be understood that I am not limited to the use of any specific means for dissipating the charge in condenser 18.

As the polarities of the voltages produced by windings 21 and 28 reverse, the potentials of the grids l9 and 22 will vary alternately from potentials negative with respect to the cathodes l8 and 2| respectively to potentials positive with respect to the cathodes, thereby causing the tubes l4 and iii to become alternately conducting and non-conducting. Since the windings 21 and 28 are oppositely connected tube ll will be conducting when tube I8 is non-conducting and vice versa. Tubes l4 and I5 may be of any suitable type employing control grids including either the vacuum or vapor arc types. In either case the passage of current is controlled by the potential of the grids. Although I prefer to utilize grid controlled discharge tubes, my invention is not limited thereto but obviously includes the use of any suitable type of current controlling means.

Fig. 2 illustrates the action in case tubes of the vapor arc or ionic discharge type are employed in which case each tube will conduct during one-half cycle and be non-conducting during the other half of the cycle of an alternating current source supplying winding 28, and the tube will change abuptly from non-conducting to the conducting condition as the grid becomes positive with respect to the cathode for the reason that conductivity results from ionization of the medium within the tube and such ionization is controlled by the grid potential. During onehalf cycle current will flow into the condenser I3 charging it to the potential existing between terminals II and I2. During the next half cycle tube It will be non-conducting, tube It will become conducting and the charge will be transferred from condenser I! to condenser iii. If the ,condenser l8 has a greater capacity than con- Fig. 2, it will be seen that during one half cycle as current is flowing into condenser l8 the potential across condenser l8 gradually rises following an exponential curve. During the next half cycle when tube I8 is non-conducting the potential will remain fixed, resulting in a series of curved and fiat portions with steps at the points A,B,C.andD. Ifthe discharge tube 29isso biased as to become conducting when the potential across condenser l8 equals that represented by the point D on the curve Fig. 2, the apparatus will respond after four cycles of a ternating current have flowed in the windingj or after four impulses have been given to the apparatus. If the source of alternating current supplied to winding 28 as a constant frequency, obviously the apparatus may be used as a timing device since each cycle represents a fixed period of time. However, the apparatus is also useful in connection with counting impulses which do not occur at fixed intervals since each impulse produces an increase in charge on. condenser l8 which remains constant for a considerable period of time and the resultant potentials will be represented by flat portions in curve Fig. 2 of varying length instead of fixed length. Obviously, the apparatus may be arranged to operate after any desired number of impulses or after the expiratior. of any desired period of time.

In Fig. 3 I have shown another manner of connecting the apparatus shown in Fig. 1. In this case the condensers are connected in series instead of in parallel and are designated by the reference characters [3' and i8. Condenser l3 has one terminal connected to the mid-point of a resistor 38 which joins cathode 18 of tube It to plate 20 of tube l5. Accordingly, a series circuit is formed from positive terminal ll of the direct current source through tube It, a portion of resistor 38, charge transferring condenser i3, charge collecting condenser l8, back to negative terminal l2 of the direct current source. When the tube It becomes conducting currents will flow, charging condenser l3 and I8. Initially, the distribution of potential between condensers l3 and I8 will depend upon the relative capacities of the condensers. When tube 15 becomes conducting condenser l3 will be discharged but the charge collected by condenser l8 will be re tained. Each time tube H becomesconducting and condenser I3 is charged condenser l8 will be raised to a higher potential which is the same result produced by the arrangement shown in Fig. 1.

Means responsive to the potential across the .plates of condenser l8 are here shown by way potential by means of a potentiometer 31 connected to a battery 36. In this case the discharge tube 1% is illustrated as controlling an alternating current source 33' instead of a direct current source 33 as shown in Fig. 1.

Either form of the apparatus shown in Figs. 1 and 3 may be employed in any arrangement where it is desired to measure time or count impulses or to control the operation of other apparatus after a predetermined time or after a predetermined number of impulses or after the apparatus itself is operated a predetermined number of times. Either form of the arrangement may also be utilized as the basis of other apparatus requiring timing mrans or counting means for its operation. It will be apparent that the number of impulses required to give a response is determined by the relative capacities of condensers l3 and IE or l3 and |6, by the voltage of the source |||2, and by the grid bias given tube 29.

Fig. 4 represents an arrangement in which an alternating current of one frequency may be converted to another of a lower frequency. After a predetermined number of cycles of one alternating current circuit, an impulse is produced which initiates a cycle in another alternating current circuit. In this arrangement additional apparatus is employed which times the second alternating current circuit in response to the frequency of the first alternating current circuit. After a predetermined number of cycles, the potential of condenser I6 raises the potential of the plate 4| and the grid 42 of a discharge tube 39 to the point where the tube 39 becomes conducting and the condenser i6 is discharged through the tube 39 and the resistor H0.

The momentary flow of current in resistor 40 momentarily creates a potential difference between the ends of the winding 44 of a trans former. After the condenser I6 is discharged the operation of the cycle counting device is repeated until the potential of the condenser l6 again reaches the predetermined value so that it is discharged through resistor 40 and another impulse is produced in winding 44 of the transformer. This operation is repeated indefinitely. An inverter 45 of any suitable type is provided in which each impulse of the winding 44 is arranged to start a flow of current in a suitable circuit in a reverse direction each time, thereby producing alternating currents having a frequency bearing a definite ratio to the frequency of the current flow in winding 26 of transformer 25.

I may, for example, use an inverter of the peak excitation type employing a pair of discharge tubes 46 and 41 preferably of the vapor arc discharge type. The power required by the inverter is supplied by a direct current source 48. The tubes joined by a reactor 49 are connected in series across the terminals of the direct current source 48. A condenser 50 and a load 5| in series form a circuit from the mid-point of reactor 49 to one terminal of the direct current source 48. The tubes 46 and 41 have their grids 52 and 53 normally negatively biased with respect to the cathodes of the tubes by means of batteries 54 and 55 respectively. The batteries 54 and 55 are connected to the secondary windings 56 and 51 which are in inductive relation with the winding 44.

Secondary windings 56 and 51 have voltages induced in them by the momentary flow of current through winding 44 which occurs whenever the condenser I6 is discharged. The windings 66 and 61 are so connected that these momentary voltages raise the potentials of the grids 62 and 53 momentarily above the potentials of the corresponding cathodes thereby making the tubes conducting in response to impulses sent through winding 44 from condenser l6.

Although the grids 52 and 63 of tubes 46 and 41 become positive simultaneously causing both the tubes to be in a conducting condition at the same time, current actually flows in only one of the tubes at a time. The action is as follows: Assuming that the condenser 50 is initially discharged, when the voltage peaks are impressed on grids 52 and 53, the tubes become conducting momentarily. Owing to the fact that the circuit including the portion 49a of reactor 49. the condenser 50 and load 5| in series with direct current source 48 has a lower inductive reactance as a result of the capacity than he circuit which includes the other portion 49b of the reactor 49, a current will tend to build up in the portion 49a before it does in the portion 49?). Since both portions have a common magnetic circuit, the same back voltage will be induced in each portion. The back voltage induced in 49b will be sufilcient to suppress the current which would tend to start flowing in 49b and tube 46- Owing to the inductive inertia effect on the current flowing in 48a. condenser 50, and load 5i which may be a tuned circuit, current will continue to flow after the condenser 50 has reached the potential of the direct current source 48. Consequently, condenser 50 will reach a potential higher than that of source 48 so that ultimately the current in tube 41 and reactor portion 49a is suppressed regardless of the conducting condition of tube 41. Since the tube 41 can pass current in only one direction, the condenser 50 cannot discharge through tube 41 back into the source 48.

The next time tubes 46 and 41 become conducting, condenser 50 will discharge through the tube 46 causing a reversal of the current flowing in the load 5|, but no current tends to flow from source 48 through tube 41 since the condenser 50 is at a higher potential than the source 48. The subsequent time the tubes become conducting current will again flow through tube 41, reactor portion 49a, condenser 50. and load 5|, tending to charge the condenser 50 and suppressing as a result of the back voltage any tendency for current flow in tube 46. In this manner the operation continues with the current flowing alternately in tubes 41 and 46 and the direction of current in load 5| being reversed each time the tubes become conducting. Although not essential to the operation it is desirable to choose values of inductance and capacity which provide a tuned circuit in order to obtain a current in load 5| having a sine wave shape. This action is repeated indefinitely and accordingly an alternating current is produced in the load 5| having a frequency which bears a predetermined relationship to the frequency in the source supplying winding 26 of transformer 25. Although I have shown the apparatus in connection with an inverter of the peak excitation type which is well known in the art, it will be understood that my invention is not limited thereto and may be used to control the operation and frequency of any suitable type of inverter.

The basic apparatus disclosed in Figs. 1 and 3 may also be used, for example, to form a portion of an electrical code selector thereby eliminating the necessity for cams or other mechanical parts and permitting the designer greater latitude in the choice of timing of the impulses or the intervals therebetween.

In Fig. 5 I have shown for the sake of illustration a switch or telegraph key 89 closing a circuit through a battery 88 and primary winding 28 of transformer 25. When the switch is closed, voltages are induced in windings 21 and 28. Since the windings 21 and 28 are oppositely connected, the grid potentials of the tubes I4 or IE are oppositely affected, the grid of one of the tubes becoming positive and causing the tube to conduct. When the switch 59 is opened, voltages of the reversed polarity are induced in windings 21 and 28, and the tube which was conducting ceases to conduct whereas the other tube becomes conducting. The operation is similar to that explained in connection with Fig. 1 so that condenser i3 is alternately charged and discharged as before, and condenser 16 is raised to a successively higher potential with each impulse. Having connected a battery and telegraph key across the primary winding 28, the apparatus of Fig. l or 3 without further change might be used as a code responsive device. However, the device would not be fully selective since the response would take place as soon as the required numbe" of impulses had been supplied and the device would therefore respond as well to an incorrect number of impulses greater than the required number. Consequently, the arrangement is modified as shown in Fig. 5 to prevent a respouse if an additional impulse is supplied.

To this end an additional charge collecting condenser 60 is connected in parallel with the condenser iB which may now be termed the intermediate condenser. A resistor BI is interposed in one of the leads connecting condensers l6 and 60 in order that condenser 60 will acquire the potential of condenser 18 only after a time delay depending upon the magnitude of resistance 6|. A discharge tube 85 is connected across condenser i6 and has its grid 88 so biased by means of battery 61 that the tube becomes conducting when condenser l8 reaches a potential corresponding to a number of impulses one greater than the correct number for the code for which the apparatus is arranged. In consequence of the time delay introduced by resistor 6|, condenser i8 is discharged upon the occurrence of a false signal before condenser has reached the potential corresponding to the number of impulses in the code.

As in the form of the apparatus previously described, when the predetermined number of impulses has been produced by switch 59, causing charge transferring condenser ll to be charged and discharged a predetermined number of times, thecondensers i8 and 60 will acquire a potential which overcomes the negative bias of grid 62 of discharge tube 83 permitting the discharge tube 63 to conduct current supplied by a source 04. Although I have shown a discharge tube 83 and a source of current 84 it will be understood that any suitable means responsive to the potential of charge collecting condenser 80 may be employed to indicate that the required number of impulses has been produced by switch 59.

Although the arrangement shown in Fig. 5 is made unresponsive when an extra impulse is supplied, even this arrangement is not fully selective. Since the extra impulse restores the apparatus to initial conditions, the operation starts over again and a response may be obtained if a certain number of additional impulses is supplied. To prevent this result the discharge tube 88 may be connected, as shown in Fig. 6, across condenser iii instead of it, but having its grid 88 connected through potentiometer 8! to the terminal of the condenser i6. Consequently, the tube 86 becomes conducting and discharges condenser 80 as soon as the potential of condenser l8 acquires a value corresponding to one more than the correct number of impulses, and the condenser 80 remains discharged, however great the potcntial of condenser It becomes. If desired, the discharge tube may be provided with an anode supply by means of the secondary winding 88 of the transformer 64, thereby charging the condenser 60 negatively whenever the potential of the condenser it exceeds the predetermined value, in order to insure neutralization of charge flowing from condenser IO. The apparatus shown in Figs. 1, 3, and 5, and in Fig. 6, so far as described, may be used to respond to a given number of impulses regardless of the time interval between impulses.

The apparatus may be made still more selective by so arranging it that it will not respond unless the impulses are received consecutively and within intervals of a predetermined normal length. This may be accomplished as shown in Fig. 6 by providing a discharge tube 10 connected in shunt to the intermediate condenser It. The tube 10 normally short-circuits the condenser i6 since the grid II is normally positively biased by means of battery 12. The apparatus is so arranged, however, that whenever an impulse is received by the winding 26 of transformer 25, the positive bias of grid II is removed and the tube remains non-conducting until a period slightly greater than the normal interval between the impulses of the code has elapsed. In order to remove the positive bias of the grid ll, condenser 13 connected between the cathode of the tube Hi and the grid battery 12 is arranged to be negatively charged whenever an impulse is received by the transformer 25. After the normal interval has elapsed the charge of the condenser 13 leaks on through resistor 14.

The condenser 13 is charged by means of a source ll controlled by a discharge tube I8 having a grid 11 normally negatively biased by means of a battery 18. The potential of the grid 11 is controlled by means of a secondary winding 19 forming a portion of the transformer 25 which comprises also the secondary windings 21 and 28 controlling the grids of tubes I4 and iii. It will be apparent that, if there is a pause in the supplying of impulses or if the impulses are discontinued after an unsuccessful or a successful attempt to operate the device, the condenser is will be discharged and the apparatus will be restored to its initial condition.

Although I have illustrated the apparatus required to respond to a single figure code only, it will be understood that my invention is not limited thereto but that the apparatus illustrated may be utilized as one of the units of a device responsive to a mode containing two or more groups of impulses.

Although I prefer to utilize discharge tubes or electric valves for controlling the charging and necessary Fig. 7 also illustrates the application of my invention to summation or totalizing and telemetering devices. A plurality o charge transferring condensers l3, iia, etc., having sources of charging current 94, 94a, etc. are arranged to be charged and to give up their charges to a charge collecting condenser I 8 in response to impulses to be totaiized. Mechanical means, for example rotating cams 85 and 95a are utilized to make and break the charging circuit through contacts 86 and 88a and to close the circuits from the charge transferring condensers l3 and Us to the charge collecting condenser i8 tnrough contacts 91 and 81a.

The operation akes place as explained in connection with the other embodiments of the apparatus described above. The rotating cam 95 which may be driven by an electrical meter, for example, the readings of which are to be totalized, alternately closes contacts 98 to charge the condenser l3 and opens the contact 98 simultaneously with closing the contact 91 in order to transfer the charge from the condenser iii to the charge collecting condenser iii. In a similar manner each impulse given the cam 95a, for example, the rotation of the shaft of a meter, transfers a charge from the condenser i3a to the charge collecting condense) Hi. When the condenser l6 has received a charge corresponding to the potential for which the discharge tube 39 is biased, the tube 39 becomes conducting. The discharge tube 39 may if desired be arranged when it becomes conducting to discharge the condenser l6 through a magnet coil 98 having a plunger SIS-cooperating with a star-wheel I carried by the shaft of a registering device lill. Accordingly, each time, a predetermined total number of impulses is supplied to the apparatus the condenser 16 is discharged and the reading of the register iiii is advanced. Each of the condensers i3 and Ba and their associated charging and circuit controlling means may be situated at a distance from the condenser i6 and each other, and connected to condenser It by conductors of any desired length. The apparatus then aflords a means for telemetering as well as totalizing.

In accordance with the provisions of the patent statutes I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What 1 claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a source of current, a grid controlled discharge tube and a pair of condensers connected in series, a second grid controlled discharge tube connected across one of said condensers, means responsive to the potential difference across the other of said condensers, and means for modifying the grid potentials of said discharge tubes alternately for the purpose of causing said tubes alternately to become conducting thereby alternately charging and discharging the first mentioned condenser and progressively charging the other of said condensers to successively higher potentials.

2. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a source of current, a charge transferring condenser receiving charges therefrom, a grid controlled discharge tube controlling the charging of said condenser, a Second grid controlled discharge tube controlling the discharging of said condenser, an intermediate condenser in circuit with said charge transferring condenser and receiving charges in accordance with the charge of said charge transferring condenser, means for modifying the grid potentials of said discharge tubes in succession in response to each impulse for the purpose of causing said tubes to become conducting successively, thereby alternately charging and discharging said charge transferring condenser and progressively charging said intermediate condenser to successively higher potentials with each impulse, a third grid controlled discharge tube arranged to discharge said intermediate condenser when more than a predetermined number of impulses is received, a charge collecting condenser and a resistor in series connected to said intermediate condenser, and means responsive to the potential of said charge collecting condenser.

3. An impulse responsive device, selectively responsive to a predetermined code of impulses comprising a source of current, a charge transferring condenser receiving charges therefrom, a grid controlled discharge tube controlling the charging of said condenser, a second grid controlled discharge tuhe controlling the discharging of said condenser, an intermediate condenser in circuit with said charge transferring condenser and receiving charges in accordance with charge of said charge transferring condenser, means for modifying the grid potential of said discharge tubes in succession in response to each impulse for the purpose of causing said tubes to become conducting successively, thereby charging and discharging said charge transferring condenser and progressively charging said intermediate condenser to successively higher potentials with each impulse, a charge collecting condenser and a resistor in series connected to said intermediate condenser, a third grid controlled discharge tube arranged to discharge said charge collecting condenser when the potential of said intermediate condenser exceeds that corresponding to a'predetermined number of impulses, and means responsive to the potential of said charge collecting condenser.

4. An impulse responsive device selectively responsive to a predetermined code of impulses, comprising a source of current, a charge tronsferring condenser receiving charges therefi. '1, a grid controlled discharge tube controlling fine charging of said condenser, a second grid controlled discharge tube controlling the discharging of said condenser, an intermediate condenser in circuit with said charge transferring condenser and receiving charges in accordance with the charge of said charge transferrng condenser, means for modifying the grid potential of said discharge tubes in succession in response to each impulse for the purpose of causing said tubes to become conducting successively, thereby charging and discharging said charge transferring condenser and progressively charging said intermediate condenser to successively higher potentials with each impulse, a charge collecting condenser and a resistor in series tonn cted to said intermediate condenser, a third grid controlled discharge tube arranged to discharge said charge collecting condenser when the potential of said intermediate condenser exceeds that corresponding to predetermined number of impulses, means responsive to the potential of said charge collecting condenser, a fourth normally conducting grid controlled discharge tube shunting said intermediate condenser, and means for causing said fourth discharge tube to become non-conducting during each impulse and for a period thereafter somewhat greater than a normal interval between impulses of the code.

5. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a condenser, means for charging said condenser to successively higher potentials in response to successive impulses, a second condenser connected to said first mentioned condenser so as to be charged therefrom, a resistor included in the connection, means responsive to the potential of said second condenser, and means for short-circuiting said first mentioned condenser when more than a predetermined number of impulses is received.

6. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a condenser, means for charging said condenser to successively higher potentials in response to successive impulses, a second condenser connected to said first mentioned condenser so as to be charged therefrom, a resistor included in the connection between said condensers, means for short-circuiting said second mentioned condenser when more than a predetermined number of impulses are supplied to the device, and means responsive to the potential of said second condenser.

7. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a condenser, means for charging said condenser to successively higher potentials in response to successive impulses, a second condenser connected to said first mentioned condenser tlnteugh resistance for the purpose of causing said second condenser to acquire the potential of the first condenser after a predetermined time delay, means responsive to the potential of said second condenser, and means for preventing a response when the interval retween impulses exceeds a predetermined time.

8. In combination, a source of current, a series condenser and a charge collecting condenser receiving charges from said source in series, means controlling the charging of said condensers, and means controlling the discharging of said series condenser, said controlling means being arranged alternately to charge and discharge said series condenser and progressively to charge said charge collecting condenser to successively higher potentials.

9. In combination, a source of current, current interrupting means, a condenser, a second condenser of greater capacity all connected in series, a second current interrupting means connected across the terminals of said first mentioned condenser, means responsive to the potential difference across said second condenser, means for controlling said current interrupting means making them alternately conducting thereby alternately charging and discharging said first mentioned condenser and progressively charging the second of said condensers to successively higher potentials.

10. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a condenser, means for charging said condenser to successively higher potentials in response to successive impulses, means responsive to the potential of said condenser, and impulse responsive means for preventing the operation of said potential responsive means in case the number of impulses supplied to the device exceeds a predetermined number.

11. An impulse responsive device selectively responsive to a predetermined code of impulses comprising in combination, a charge transferring condenser, a charge collecting condenser in circuit therewith, means for alternately charging and discharging said charge transferring condenser and charging said charge collecting condenser by an amount dependent upon the charge of the first condenser to successively higher potentials in response to successive impulses, means responsive to the potentials of said condenser, and impulse responsive means for preventing the operation of said potential responsive means in case the number of impulses supplied to the device exceeds a predetermined number.

12. In a condenser charging system, a storage condenser, a series condenser, a source of alternating current, a charging circuit for the condensers in series, a discharge circuit for the series condenser, and means responsive to each wave of alternating current of one polarity to cause current to flow in the charging circuit of the condensers, and responsive to each wave of current of the opposite polarity for causing said series condenser to discharge current over the discharge circuit.

13. Apparatus for investigating properties of electrical impulses comprising a condenser, a second condenser 01 greater capacity than said first condenser, means responsive to each impulse for charging said condensers in series, means also responsive to each impulse for discharging said first condenser, means for discharging said second condenser responsive to a predetermined charge accumualtion thereon, a measuring device, and means in the discharge circuit of said second condenser for controlling said device.

14. An impulse responsive device selectively responsive to a predetermined code of impulses comprising a condenser, means for charging said condenser to successively higher potentials in response to successive impulses, means responsive to the potential of said condenser, and a time responsive means reset by each impulse for preventing the operation of said potential responsive means in response to a predetermined delay before the reception of a succeeding impulse.

ALAN S. FI'IZ GERALD.

CERTIFICATE OF CORRECTION.

Patent No. 2,110,015., March 1, 1938.

' ALAN S. FITZ GERALD.

Itis hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5 second column, line 51, after the word "current" insert to; page second column,

line 61;, for "mode" read code; page 5., second column, line 58, claim 1 for "transferrng" read transferring; line 72, same claim, after "to" insert the article "a"; page 6, second column, line 25, claim 11., for "potentials" Y read potential; and that the said Iaettere Patent should be read with these corrections therein that the same may' conform to the record of the casein the Patent Office.

; Signed and sealed this 26th day of April, A. D. 1938.

- Henry Van Arsdale, (Seal) Acting Comniasioner of Patents vi I cERTiF CATE 0F CORRECTION. Patent no.2,11oi, o1 5.', I March 1, 19 s.

I ALANS. F mz GERALD.

v It'is her eb y certifiwjthai; g or gpfiears in the printed specificatibh of the above numbered patent 'eqfi iring' cprrection as fbllows; Page 5 second column, 1111551, aftei"jihwbrdfncuirnt iziseft to; page 1;, second column,\ 7 line 6L; for."11ode 're ad cbd} page second column, line 58, claim for "transfe rrng" raid transferring; lin 72, same claim, after Y'to" insert the 7 article;- -"a"; page'; sconcl olumn, line 25;. claim 11., for "potentials" rm potential; that th'eraaid Ii'etters Patent ghofild be read with 11 85 cgrre'ct ioriis therein that the? slime ion fo rm tothe record of the asein V nm g@mg m 26thidayfof Apr11QA'. 1). 19 y HenryVa n Arsciaie,-. Acting CpnnnisaioneifQi' Patents 

